Back at the new iPad launch in March, Apple, as usual, invited a few third-party developers to show off upcoming apps. One of them was Autodesk, which demonstrated an intriguing drawing program called SketchBook Ink. After a few weeks’ delay, the company is releasing the app today; it provided me with an advance copy for review.

A stablemate of the company’s excellent, feature-packed SketchBook Pro, Ink pretty much does one thing: It lets you sketch with your finger (or, better yet, a pen) to draw with virtual ink that settles onto the page as you draw, leaving interesting little imperfections as if it were seeping into the paper.

And Ink has one noteworthy feature which SketchBook Pro doesn’t — the drawings you create aren’t bitmaps. Instead, they’re resolution-independent, so you can zoom in as much as you like and can save them to the iPad’s Photo Library, Dropbox, iTunes or email at resolutions that go beyond even the new iPad’s 2048-by-1536 pixels without introducing any jaggies. You can opt for up to 11,336-by-8727 resolution; that’s especially useful if you plan to eventually print your creation.

The program gives you seven different penstrokes, each of which behaves differently and leaves a line whose thickness is determined by the velocity with which you sketch. You can adjust their width and color, and can draw on top of a photo or other bitmapped image imported from the tablet’s Photo Library.

And that’s about it. SketchBook Ink doesn’t have any other drawing tools, or layers or the ability to send images to Facebook or other social networks. And the “ink,” unlike real ink, is completely opaque. There’s no transparency if you lay down one line on top of another. Other than Undo (which I found surprisingly slow), there’s also no way to remove a line once you’ve put it on the paper without also erasing whatever’s below it.

Even without many frills, this app is fun and fluid, and you can create some nifty effects. But I hope that Autodesk beefs it up in future releases. Just a few more features — especially layers — would let you more easily create much more sophisticated works of inky art.

SketchBook Ink is officially a $4.99 program, but for now, it’s on sale for $1.99. If you like to draw on an iPad, buying it and trying it is a no-brainer.